The number I remember seeing was that on average, app users are seven times more profitable than web users. Sorry, no citation.
I suspect there’s some selection bias in that regular/loyal users of a particular product or service are more likely to install the app, but it also affords the company greater access to send notifications and collect data. On the rare occasion that I install some random company’s app for a specific benefit, I remove it when I’m done.
I remember getting a boarding pass from an airline that was only offered in their app or printed at the airport, no email/download image/PDF option. I didn’t have to install their app, but I would have had to waste time at the airport otherwise. I removed it when I was done and left it a negative review.